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A200554 Number of -n..n arrays x(0..3) of 4 elements with zero sum and nonzero second differences. 1
14, 76, 200, 446, 836, 1368, 2134, 3140, 4368, 5942, 7852, 10064, 12734, 15836, 19320, 23374, 27956, 33000, 38726, 45076, 51968, 59654, 68060, 77088, 87022, 97772, 109224, 121694, 135076, 149240, 164534, 180836, 198000, 216406, 235916, 256368 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 2 of A200553.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = 2*a(n-1) -a(n-2) +2*a(n-3) -4*a(n-4) +2*a(n-5) -a(n-6) +2*a(n-7) -a(n-8).

Empirical g.f.: 2*x*(7 + 24*x + 31*x^2 + 47*x^3 + 24*x^4 + 9*x^5 + 2*x^6) / ((1 - x)^4*(1 + x + x^2)^2). - Colin Barker, May 21 2018

EXAMPLE

Some solutions for n=3:

.-2....2....2...-1....2...-3...-2...-2....1...-3....0...-1....1....2...-2....2

..1...-3...-2....0...-1....3...-1....1....0....3...-1...-1...-2...-2...-1....1

..2....1....0...-1....0....2....3...-2....1...-1....2....1....0...-3....2...-3

.-1....0....0....2...-1...-2....0....3...-2....1...-1....1....1....3....1....0

CROSSREFS

Cf. A200553.

Sequence in context: A093567 A296996 A270704 * A152100 A173962 A200547

Adjacent sequences:  A200551 A200552 A200553 * A200555 A200556 A200557

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 19 2011

STATUS

approved

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Last modified October 17 22:48 EDT 2018. Contains 316297 sequences. (Running on oeis4.)